1. Field of the Invention
The present invention relates generally to medical apparatus and methods. More particularly, the present invention relates to catheters having guide wire tubes disposed within expandable structures for facilitating catheter exchange over a guide wire.
Percutaneous transluminal angioplasty procedures have become a therapy of choice for treating stenosed regions in the patient's vasculature, particularly the coronary vasculature. Recently, the use of such angioplasty procedures has often been combined with stent placement and/or radiation treatment to inhibit restenosis and hyperplasia following angioplasty. When performing such multiple, sequential treatments, it is usually necessary to “exchange” catheters which are used to perform each of the procedures. That is, the initial angioplasty treatment will be performed using a balloon angioplasty catheter. After the angioplasty is completed, a second catheter carrying a stent or other vascular prosthesis must then be introduced to the treatment site. Introduction of the second catheter involves first removing the balloon angioplasty catheter and then placing the second catheter in the treatment region. Optionally, a third catheter may then be exchanged for the second in order to perform radiation or other treatments in order to inhibit hyperplasia.
In performing such multiple, sequential treatments, most physicians prefer to leave a “guidewire” in place to the treatment location. A guidewire is a small diameter, highly flexible wire that can be steered to the target location through the vasculature and which then acts as a guide path for introducing and positioning the balloon angioplasty and other interventional catheters.
In the early days, balloon angioplasty catheters were designed to be introduced into the vasculature in an “over-the-wire” manner. That is, the catheters were designed to have passages, commonly referred to as guidewire lumens, which extended the entire distance from the distal end of the catheter to the proximal end of the catheter. The catheter could then be loaded over a proximal end of a guidewire which was already in place in the patient and then advanced over the guidewire until a distal end of the catheter reached the target site. While functional, the need to maintain control of the guidewire while the interventional catheter was being introduced meant that the guidewire had to have an excess length outside of the patient which was greater than the length of the catheter being introduced. If the length were any shorter, the treating physician would not be able to hold on to the guidewire as the catheter was being introduced. Although necessary for catheter introduction, the excess guidewire length (optionally in the form of a detachable extension) was very difficult to manage during other parts of the treatment.
To overcome the difficulties associated with very long guidewires “rapid exchange” or “monorail” balloon angioplasty catheters were developed. A number of specific designs have been developed over the years, and the rapid exchange catheters generally have a shortened guidewire lumen which extends from a distal tip of the catheter to an exit port located closer to the distal end of the catheter than to the proximal end. By reducing the length of the guidewire lumen, the need for a guidewire having excess length outside of the patient is also reduced.
The use of rapid exchange catheters has become wide spread, and they have proven to be particularly valuable for use as stent delivery catheters. Stent delivery catheters are normally used after an initial angioplasty treatment. In such cases, the angioplasty catheter will be removed and exchanged for the stent delivery catheter. Use of an angioplasty catheter having a rapid exchange design facilitates removal of the angioplasty catheter over short guidewires. Similarly, use of the stent delivery catheter having a rapid exchange design facilitates introduction of the catheter over the guidewire which remains in place in the patient.
Most rapid exchange balloon angioplasty catheters have one of two basic designs. The first design was disclosed initially in U.S. Pat. No. 4,762,100 to Bonzel. In the Bonzel design, an angioplasty balloon catheter having a balloon at the distal end of the shaft is provided with a second guidewire tube positioned through the balloon in parallel with the distal tip of the shaft. While functional, this design adds to both the diameter and stiffness of the distal tip of the shaft, both of which properties make it more difficult to introduce the catheter to narrow regions of the coronary and other vasculature. The second general design was first disclosed in U.S. Pat. No. 5,048,548 to Yock et al. In the Yock design, the shaft of an angioplasty catheter is provided with at least two lumens, a balloon inflation lumen and a distal guidewire lumen. Usually, the two lumens are disposed in parallel over at least a portion of the length of the catheter body, again increasing the diameter and potential of the stiffness of the catheter. Moreover, the provision of a “notch” or hole in the side of the catheter body can cause the body to kink when delivered under certain conditions.
For these reasons, it would desirable to provide improved and alternative apparatus, methods, kits, and the like for permitting the exchange of catheters over guidewires in a “rapid exchange” or other facilitated manner. It would be particularly desirable to provide improved balloon angioplasty and other catheters which can be introduced over a shortened guidewire without the need to provide a guidewire lumen anywhere in the catheter body and/or to provide a separate guidewire tube in parallel with or overlapping with the catheter body. Such designs should be compatible with catheters having very low profile distal ends, i.e., diameters of 5 Fr, 4 Fr, and even below, at their distal ends. At least some of these objectives will be met by the invention described and claimed hereinafter.
2. Description of Background Art
Rapid exchange catheters having guidewire exchange devices are described in U.S. Pat. Nos. 5,281,203; 5,571,094; and 5,919,175. Sleeves for positioning stents, drug infusion tubes, imaging transducers, and other interventional devices over balloon angioplasty catheters are described in U.S. Pat. Nos. 5,776,191; 5,810,869; and PCT Publication WO97/07756. Rapid exchange and related catheters are described in U.S. Pat. Nos. 6,605,057; 6,533,754; 6,527,789; 6,569,180; 6,585,657; 6,478,807; 6,361,529; 6,277,093; 6,273,879; 6,248,092; 6,165,197; 6,129,708; 6,036,715; 6,056,722; 6,027,475; 6,007,517; 5,980,486; 5,980,484; 5,947,927; 5,921,971; 5,935,114; 5,919,164; 5,891,056; 5,855,685; 5,846,246; 5,833,659; 5,830,227; 5,827,241; 5,807,355; 5,814,061; 5,769,868; 5,749,888; 5,738,667; 5,728,067; 5,709,658; 5,685,312; 5,626,600; 5,620,417; 5,607,406; 5,554,118; 5,545,134; 5,531,690; 5,501,227; 5,496,600; 5,472,425; 5,468,225; 5,460,185; 5,458,613; 5,451,223; 5,443,457; 5,415,639; 5,413,559; 5,395,335; 5,383,853; 5,364,376; 5,350,395; 5,346,505; 5,336,184; 5,334,147; 5,328,472; 5,300,085; 5,380,283; 5,281,203; 5,263,963; 5,232,445; 5,195,978; 5,135,535; 5,061,273; 5,048,548; 4,762,129; 4,988,356; 4,947,864; 4,762,100; 4,748,982; US2003/0208221; US2003/012301; US 2002/0004053; and WO 99/13935.